Casavant N C, Lee R N, Sherman A N, Wichman H A
Department of Biological Sciences, University of Idaho, Moscow, Idaho 83844, USA.
Genetics. 1998 Sep;150(1):345-57. doi: 10.1093/genetics/150.1.345.
The large number of L1 [long interspersed elements (LINE)-1] sequences found in the genome is due to the insertion of copies of the retrotransposon over evolutionary time. The majority of copies appear to be replicates of a few active, or "master" templates. A continual replacement of master templates over time gives rise to lineages distinguishable by their own unique set of shared-sequence variants. A previous analysis of L1 sequences in deer mice, Peromyscus maniculatus and P. leucopus, revealed two active L1 lineages, marked by different rates of evolution, whose most recent common ancestor predates the expansion of the Peromyscus species. Here we exploit lineage-specific, shared-sequence variants to reveal a paucity of Lineage 2 sequences in at least one species, P. californicus. The dearth of Lineage 2 copies in P. californicus suggests that Lineage 2 may have been unproductive until after the most recent common ancestor of P. californicus and P. maniculatus. We also show that Lineage 1 appears to have a higher rate of evolution in P. maniculatus relative to either P. californicus or P. leucopus. As a phylogenetic tool, L1 lineage-specific variants support a close affinity between P. californicus and P. eremicus relative to the other species examined.
基因组中存在大量的L1[长散在重复序列（LINE）-1]序列，这是由于逆转座子在进化过程中不断插入造成的。大多数拷贝似乎是少数活跃的或“主”模板的复制。随着时间的推移，主模板的不断更替产生了一些谱系，这些谱系可以通过它们各自独特的共享序列变体集来区分。之前对鹿鼠（白足鼠和加州鹿鼠）L1序列的分析揭示了两个活跃的L1谱系，其进化速率不同，它们最近的共同祖先早于白足鼠物种的扩张。在这里，我们利用谱系特异性的共享序列变体来揭示至少一个物种（加州鹿鼠）中第2谱系序列的匮乏。加州鹿鼠中第2谱系拷贝的缺乏表明，第2谱系在加州鹿鼠和白足鼠最近的共同祖先之后才开始活跃。我们还表明，相对于加州鹿鼠或白足鼠，第1谱系在白足鼠中的进化速率似乎更高。作为一种系统发育工具，L1谱系特异性变体支持加州鹿鼠和荒漠鹿鼠相对于其他被研究物种之间存在密切的亲缘关系。
